You know how pizza places offer "meat lovers" or "veggie lovers" pizzas, where they just cram every single ingredient of a certain type that they have in the refrigerator onto a pie? Legends of Pegasus is kind of like that: it features a lot of elements that 4X aficionados might enjoy in the right context, but they're all just kind of slapped together in a way that doesn't allow them to complement each other. It's pizza that requires a fork and a knife to eat when you ought to be able to just pick up a slice and easily slide it into your mouth.
Legends of Pegasus' storyline relies heavily on tried-and-true sci-fi tropes, particularly a Battlestar Galactica-esque survival/flight theme. At the beginning of the game, you are informed that Earth has been conquered in a surprise attack by an unknown alien force, and a small flotilla of ships has managed to escape through a wormhole. You command that flotilla, and, as luck would have it, you've got a colony ship with you. You need to colonize habitable planets, research new technologies, build bigger and better ships, and fight off constant attacks from aliens seemingly bent on hostility. It's all very hackneyed, including the few plot "twists" that you see coming from light years away.
All that said, the storyline is admittedly secondary to the gameplay, but Legends of Pegasus doesn't score many points for itself there, either. Played on large maps of fictional solar systems, Legends of Pegasus tries to replicate the feel of http://www.gamespot.com//'s GUI, but because Legends of Pegasus is primarily turn-based (only battles take place in real time) and because its menus and controls are terribly arcane and unintuitive, it fails to give you much more than a general inkling of Sins' brilliant interface. Zooming, for example, a virtually limitless function in Sins, is strictly limited in Legends of Pegasus. This makes finding items of interest (such as waypoints or resource fields) a laborious, scrolling process. For some things, like your ships or asteroid fields, you can use predesignated icons to jump directly to them, but then you're likely to lose sight of whatever it is you want to be focused on at the same time, also resulting in needless scrolling and clicking.
There's the planet management interface too, wherein you designate what you want your colonies to build and what kinds of resource allocation you want them to have, and you can see what exactly they're generating for you in terms of revenue, science, and ships. This interface is lifted almost pixel for pixel from http://www.gamespot.com//, but unlike that game, Legends of Pegasus fails to provide you with meaningful information about what your colony-based choices mean for the future. Sure, the game has rollover tips with what each building does, but with limited space to build and an extremely limited budget, it's never clear why you'd choose X over Y.
Speaking of limited budgets, Legends of Pegasus operates in a strange ecosystem whereby the survivors of Earth's demise, desperately escaping from an alien threat, completely dependent upon the shreds of the navy they have left to protect them, are nevertheless apparently charging that navy money for everything from ship building to production of shelters for their own use. Citizens pay taxes to the interim government, but if you raise taxes too high, their morale drops, which has some unexplained further negative effect. This is your only way to make money--without which you cannot build more structures and you cannot build any ships.